Mexican officials said they will allocate nearly 250 million pesos - about $20 million - to upgrade infrastructure south of the Mariposa Land Port of Entry in Nogales.

Mariposa is the busiest commercial border crossing in Arizona, with hundreds of truck crossings daily.

The U.S. government is spending about $200 million to upgrade its side of the port.

Nogales, Ariz., Mayor Arturo Garino said construction on the U.S. side is expected to be complete in November, but work on the Mexican side has yet to start.

“They haven’t done anything yet," Garino said. "So there was a concern there, not only from their side but also from our side ... that they weren’t going to be able to get some of the work done."

But Garino said he was reassured by Mexican officials when he attended a series of meeting across the border recently at which plans and funding sources were discussed for beginning the upgrades south of the line.